Silicon-based composite anodes for high energy density, high cycle life solid-state lithium-ion battery

ABSTRACT

High energy density and long cycle life all solid-state electrolyte lithium-ion batteries use ceramic-polymer composite anodes which include a polymer matrix with ceramic nanoparticles, silicon-based anode active materials, conducting agents, lithium salts and plasticizer distributed in the matrix. The silicon-based anode active material are anode active particles formed by high energy milling a mixture of silicon, graphite, and metallic and/or non-metallic oxides. A polymer coating is applied to the particles. The networking structure of the electrolyte establishes an effective lithium-ion transport pathway in the electrode and strengthens the contact between the electrode layer and solid-state electrolyte resulting in higher lithium-ion battery cell cycling stability and long battery life.

FIELD OF THE INVENTION

The present invention is generally directed to solid-state lithium-ionbatteries and, more particularly, to silicon-based composite anodes thatare infiltrated with a network of mechanically resilient,high-ionic-conductivity electrolyte, which serves as a lithium-iontransport pathway within the electrode and strengthens the contactbetween the electrode layer and solid-state electrolyte separator.All-solid-state lithium-ion batteries employing the silicon-basedcomposite anodes exhibit improved cycling stability and longer lifetimesbecause of silicon deformation confinement/buffering duringcharging/discharging.

BACKGROUND OF THE INVENTION

Lithium-ion secondary batteries typically use carbon, such as graphite,as the anode electrode. Graphite materials are very stable and exhibitgood cycle-life and durability but graphite has a theoretical lithiumstorage capacity of only about 372 mAh/g. This low storage capacityresults in poor energy density of the lithium-ion battery.

Silicon, as an anode material, offers a theoretical capacity of 4200mAh/g that is approximately eleven times that of graphite anodes.However, typical silicon anodes have a low cycle life due to thestresses associated with the large changes in volume of 300% as thelithium ions are transported into and out of the silicon anode duringthe lithiation and delithiation process over repeated charging anddischarging cycles. In particular, the repeated volume change causes Siparticle isolation, active material and conductive material looseness,active material crack, and anode sheet crack.

In particular, with all solid-state lithium-ion batteries, the anodeactive material is placed between two solid components: the solidelectrolyte separator layer and the metal current collector. The volumeexpansion of Si anode particles leads to mechanical degradation andelectric contact loss which results in continuous capacity losses andpoor cycling performance. The volume changes to Si anodes alsointroduces associated solid electrolyte interphase (SEI) instability. ASEI is formed on the surface of Si particles during the delithiation(charging) processes when the volume of Si particles expands. In thelithiation (discharging) process, as the Si particles shrink, the formedSEI layer breaks down into separate pieces, leading to the exposure offresh Si surface in the electrolyte. In the later delithiation andlithiation cycles, new SEI layers continuously form on the Si particlesurface and break down. The SEI material accumulates as the SEI layersget thicker with each cycle. The batteries exhibit high overpotentialfor lithiation and accelerate electrolyte consumption, and the Si activematerials lose intimate contact. These batteries are characterized bycapacity losses and poor cycling life.

SUMMARY OF THE INVENTION

The present invention is based in part on the development ofelectrolyte-infiltrated silicon-based composite anodes that areparticularly suited for all solid-state lithium-ion batteries (ASSLiBs).The infiltrated electrolyte has high ionic conductivity and a robustpolymer networking structure. The Si-based anode could be fabricatedusing established industry lines and the resultant anode sheet can bedirectly incorporated into the manufacturing of ASSLiBs that exhibithigh energy density, long cycle life, and high charge/discharge rates.

In one aspect, the invention is directed to ceramic-polymer compositeanodes that include: (i) a polymer matrix, (ii) ceramic nanoparticlesthat are distributed in the polymer matrix, (iii) a silicon-based anodeactive material that is distributed in the polymer matrix, (iv) aconducting agent that is distributed in the polymer matrix, (v) lithiumsalt and (vi) plasticizer. In one embodiment, the silicon-based anodeactive materials are anode active particles formed of a mixture ofsilicon, graphite, and metallic and/or non-metallic oxides. The anodeactive particles can include a polymer coating. A preferred technique offabricating the anode active particles comprises high energy ballmilling of the silicon, graphite and oxides to form a precursor mixturethat is subjected to high temperature annealing. The anode activeparticles are coated with a polymer coating. The high-capacity Si-basedanode active materials can be readily manufactured in large-scalefacilities for use in ASSLiBs.

In another aspect, the invention is directed to an electrochemical cellthat includes:

-   -   (a) ceramic-polymer composite anode that includes: (i) a first        polymer matrix, (ii) a first ceramic nanoparticles that are        distributed in the first polymer matrix, (iii) a silicon-based        anode active material that is distributed in the first polymer        matrix, (iv) a first conducting agent that is distributed in the        first polymer matrix, (v) first lithium salt and (vi) first        plasticizer;    -   (b) a cathode which includes a cathode active material and        lithium; and    -   (c) an electrolyte there between.

In yet another aspect, the invention is directed to a solid-statelithium-ion battery having a plurality of unit cells, each unit cellincludes:

-   -   (a) an electrolyte-infiltrated composite silicon-based anode        that includes: (i) a first polymer matrix, (ii) first ceramic        nanoparticles that are distributed in the first polymer        matrix, (iii) a first lithium salt, (iv) a first        plasticizer, (v) a silicon-based anode active material that is        distributed in the first polymer matrix, (vi) a first conducting        agent that is distributed in the first polymer matrix, and (vii)        a first binder if the weight ratio of the anode active material        is greater than 80 wt %;    -   (b) an electrolyte-infiltrated composite cathode that        includes: (i) a second polymer matrix, (ii) second ceramic        nanoparticles that are distributed in the second polymer        matrix, (iii) a lithium salt, (iv) a second plasticizer, (v) a        cathode active material that is distributed in the second        polymer matrix, (vi) a second conducting agent that is        distributed in the second polymer matrix and (vii) a second        binder if the weight ratio of the cathode active material is        greater than 80 wt %; and    -   (c) interposed the between the anode and the cathode, a        solid-state electrolyte which comprises a ceramic-polymer        composite electrolyte membrane that includes: (i) a third        polymer matrix, (ii) third ceramic nanoparticles with diameters        that range from 10 to 2000 nm and that are distributed in the        third polymer matrix, (iii) third plasticizer (iv) third lithium        salt, wherein the third ceramic nanoparticles are selected from        the group consisting of ceramic materials having the basic        formula Li₇La₃Zr₂O₁₂ (LLZO) and derivatives thereof wherein at        least one of Al, Ta or Nb is substituted in Zr sites of the        Li₇La₃Zr₂O₁₂.

In a further aspect, the invention is directed to a process forfabricating a solid-state lithium-ion battery cell which includes:

-   -   (a) providing a ceramic-polymer-infiltrated composite        silicon-based anode that includes: (i) a first polymer        matrix, (ii) first ceramic nanoparticles that are distributed in        the first polymer matrix, (iii) a first lithium salt, (iv) a        first plasticizer, (v) an anode active material that is        distributed in the first polymer matrix, (vi) a first conducting        agent that is distributed in the first polymer matrix, (vii) a        first binder if the weight ratio of the anode active material is        greater than 80 wt %;    -   (b) providing a ceramic-polymer-infiltrated composite cathode        that includes: (i) a second polymer matrix, (ii) second ceramic        nanoparticles that are distributed in the second polymer        matrix, (iii) a second lithium salt, (iv) a second        plasticizer, (v) a cathode active material that is distributed        in the second polymer matrix, (vi) a second conducting agent        that is distributed in the second polymer matrix, (vii) a second        binder if weight ratio of cathode active material is high        greater than 80 wt %; and    -   (c) forming a sold-state electrolyte between the cathode and        anode which includes ceramic-polymer composite electrolyte        membrane that comprises: (i) a third polymer matrix, (ii) third        ceramic nanoparticles with diameters that range from 10 to 2000        nm and that are distributed in the third polymer matrix, (iii)        third plasticizer (iv) third lithium salt, wherein the third        ceramic nanoparticles are selected from the group consisting of        ceramic materials having the formula Li₇La₃Zr₂O₁₂ (LLZO) and        derivatives thereof wherein at least one of Al, Ta or Nb is        substituted in Zr sites of the Li₇La₃Zr₂O₁₂.

In the inventive electrochemical cell, the thickness of the Si-basedanode can be reduced by 10-25% to that of a conventional graphite anode.The total thickness of the cell can be reduced by 35-40% and the totalweight can be reduced by 25-30%, resulting from the combination ofhigh-capacity Si-dominant anode and high-ionic-conductivity solid-stateelectrolyte (SSE). The inventive electrochemical cell offers high cyclelife, which is attributable to the resilience electrolyte confinedSi-based material and the intimate contact between the Si-based anodeand the SSE layer. The polymeric networking structure of the electrolytein the Si-anode serves as ionic conductive pathways for electrons andLi⁺ transport for active material particles during thelithiated/delithiated process. The continuous Li⁺ conductive network inthe Si anode composite produces an anode with higher energy/powerperformance. The crosslinking structure of the polymeric network orpolymer matrix strongly binds all of the Si-based anode components. Thecomposite Si-based anode and composite cathode form good physicalinterfacial contacts with the composite electrolyte membrane forimproved rate performance and cycling stability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a process for fabricating Si-based composite anode activematerials that are coated with a polymer (e.g. PVA) coating.

FIG. 2A is a scanning electron microscope (SEM) of pristine Si anodeactive materials.

FIG. 2B is a SEM of Si-based anode active materials without PVA coating

FIG. 2C is a SEM of pristine Si anode active materials with PVA coating.

FIG. 3 depicts the networking structure of an electrolyte and theresultant electrolyte-infiltrated composite Si-based anode.

FIG. 4 shows a tape-casting system for preparing the Si-based compositeanode.

FIG. 5A is an electrochemical cell structure.

FIG. 5B is an exploded view of a coin cell.

FIG. 5C is a coin cell.

FIG. 5D is a multiple unit cell structure for a pouch cell.

FIG. 6 is a schematic illustration comparing an ASSLiB having anelectrolyte-infiltrated Si-based composite anode to a conventionalliquid Li-ion battery.

FIGS. 7A and 7B are charge-discharge profiles and cycling profiles,respectively, for a half coin cell with the electrolyte-infiltratedSi-based anode and solid-state electrolyte.

FIGS. 8A and 8B are charge-discharge profiles for coin cells withLiMn_(1.5)Ni_(0.5)O₄ (LNMO) cathodes and different anodes.

FIGS. 9A and 9B are cycling profiles for coin cells with LNMO cathodesand different anodes.

FIGS. 10A and 10B are the charge-discharge profiles and cyclingstability profiles, respectively, for coin cells withLiNi_(0.8)Co_(0.1)Mn_(0.1)O₂ (NCM811) cathodes.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

This invention is directed to ceramic-polymer electrolyte infiltratedsilicon-based composite anodes that are particularly suited for use inlithium-ion electrochemical cells and batteries. The mechanicallyresilient high-ionic-conductivity electrolyte forms a 3-dimensionalnetworking structure within the silicon-based composite anode. Thehomogeneously distributed components in the polymer matrix establish aneffective lithium-ion transport pathway in the Si-based composite anode.

The ceramic-polymer composite anode comprises: (i) a polymer matrix,(ii) ceramic nanoparticles that are distributed in the polymer matrix,(iii) a silicon-based anode active material that is distributed in thepolymer matrix, (iv) a conducting agent that is distributed in thepolymer matrix, (v) lithium salt, (vi) plasticizer, and (v) optionally,a binder.

The polymer matrix is formed from a mixture of monomers, oligomers orpartial polymers thereof (collectively referred to as polymerprecursors). Preferred polymer matrices comprise poly(ethylene oxide)(PEO), poly(ethylene glycol diacrylate) (PEGDA), poly(acrylonitrile(PAN), polysiloxane, poly(vinylidene fluoride-co-hexafluoropropylene)[P(VDF-HFP)], poly(methyl methacrylate) (PMMA), and mixtures thereof.The ceramic-polymer composite anode typically includes 0.1 to 10 wt %and preferably 1 to 6 wt % polymer matrix.

The ceramic nanoparticles comprise lithium metal oxides with diametersthat range from 10 nm to 2000 nm. Preferred ceramic nanoparticlesinclude Li₇La₃Zr₂O₁₂ (LLZO) and derivatives thereof wherein specificquantities of Al, Ta and/or Nb are substituted at the Zr sites.Derivatives include, for example,Al_(x)Li_(7-x)La₃Zr_(2-y-z)Ta_(y)Nb_(z)O₁₂ where x ranges from 0 to0.85, y ranges from 0 to 0.50 and z ranges from 0 to 0.75, wherein atleast one of x, y and z is not equal to 0, and mixtures thereof.Particularly preferred ceramic nanoparticles areAl_(x)Li_(7-x)La₃Zr_(1.75)Ta_(0.25)O₁₂ (x ranges from 0.01 to 0.85) andLi₇La₃Zr_(2-z)Nb_(z)O₁₂ (z ranges from 0.01 to 0.60) which exhibitimproved the ionic transport in the electrode. 10. Preferred ceramicnanoparticles include Al_(x)Li_(7-x)La₃Zr_(2-y-z)Ta_(y)Nb_(z)O₁₂ whereinx ranges from 0 to 0.85, y ranges from 0 to 0.50, and z ranges from 0 to0.75, wherein at least one of x, y and z is not equal to 0, and mixturesthereof. Preferred ceramic nanoparticles have a tunable size rangingfrom 10-2000 nm. The ceramic-polymer composite anode typically includes0.1 to 15 wt % and preferably 1 to 5 wt % ceramic nanoparticles.

LLZO and derivatives thereof are commercially available, such as fromMillipore Sigma (St. Louis, MO) and MSE Supplies (Tucson, AZ).Derivatives of LLZO can be manufactured by standard solid-statetechniques using different proportions of Al₂O₃, Ta₂O₅, and/or Nb₂O₅.For example, Al_(x)Li_(7-x)La₃Zr_(1.75)Ta_(0.25)O₁₂ wherein x rangesfrom 0 to 0.85 is synthesized by mixing stoichiometric amounts ofstarting powders including LiOH·H₂O, La₂O₃, ZrO₂, Al₂O₃ and Ta₂O₅ andmilling the mixture via high energy ball milling in ethanol media for8-12 hrs. Zirconia balls (average diameter of 5 mm) balls at aball-to-powder weight ratio of about 20:1 and about 360 rpm millingspeed. After milling, the collected slurry is dried (80° C., 2-3 hrs.),crushed, and sieved (through a 200 mesh), and calcined at about 900° C.for 6 hours to fully decompose LiOH. The as-calcined powders are thenball-milled again in ethanol for 6-12 hrs. Planetary ball mill was used,followed by drying process. The dried powders were pressed into pelletswith diameters of about 9.5 mm at about 300 MPa, and then sintered witha temperature range from 800° C. to 1150° C. for about 4 hrs. to obtainparticles with size from 100 nm to 2000 nm. Both calcination andsintering processes are carried out with samples in alumina cruciblescovered by alumina lids, and the pellets are embedded in correspondingmother powder in order to mitigate losses of volatile components andaccidental contamination.

The lithium salt is any lithium salt suitable for solid lithiumelectrochemical cells. These include, for example,bis(trifluoromethane)sulfonamide lithium salt (LiTFSi), lithiumhexafluorophosphate (LiPF₆), lithium hexafluoroarsenate (LiAsF₆),LiClO₄, lithium bis(oxalate)borate (LiBoB), and mixtures thereof. Theceramic-polymer composite anode typically includes 0.1 to 10 wt % andpreferably 1 to 5 wt % lithium salt.

The conducting agent is an electronically conductive material that ispreferably made of carbon, in particular elemental carbon. Theelectronically conducting agent can be, for example, carbon black. Theceramic-polymer composite anode typically includes 1 to 15 wt % andpreferably 3 to 9 wt % conducting agent

The plasticizer is a compound that is preferably solid at roomtemperature (20° C.) and serves as a liquid medium in which the polymerprecursors can polymerize to form a polymer matrix. Preferredplasticizers are organic compounds such as succinonitrile (SCN),sulfolane (SL), ethylene carbonate (EC), dimethyl sulfoxide (DMSO),glutaronitrile (GN), propylene carbonate (PC), and mixtures thereof. Theceramic-polymer composite anode typically includes 0.1 to 20 wt % andpreferably 1 to 10 wt % plasticizer.

A binder can be used in the electrolyte-infiltrated Si-based compositeanode if active material weight percentage is high (for example, >50 wt%). Preferred binders can be polyacrylic acid (PAA), polyvinyl alcohol(PVA), and the mix of thereof. Specifically, the combination of PAA andpolyvinyl alcohol (PVA) (PAA-PVA) (PAA: PAA-PVA=50% to 90 wt %), and thecombination of partially neutralized PAA (pnPAA) and PVA (pnPAA-PVA)(pnPAA: pnPAA-PVA=50% to 90 wt %). The combination of PAA and PVAsolution realize the strong adhesion properties of PAA and mechanicalrobustness of PVA. The resultant PAA-PVA binder can overcome technicalchallenges faced by the traditional PVDF binder, such as brittleness,short service life, and poor interface adhesion. The PAA-PVA binder inSi-based composite anode shows higher stiffness, adhesion strength andelectrochemical performance in the forms of longer and more stablecycling life. The ceramic-polymer composite anode typically includes 0to 10 wt % and preferably 1 to 5 wt % binder.

To further enhance the rheological properties and electrode porosity ofPAA-PVA binder, Na ions (Na⁺) can be added to the PAA solution topartially neutralize PAA with a neutralization degree of 5-10%, prior tomixing with PVA solution. PAA polymer chains tend to “self-bond” throughits own hydrogen bond. The introduction of NaOH to the PAA solutionreduces this situation of PAA. Large amount of H⁺ are consumed with theaddition of OH⁻. The electrostatic repulsion between neighboringdissociated carbonxylate (—COOH) will make the polyacrylate chainstretched, leading to the enhanced rheological properties of PAAsolution. Furthermore, acidic condition has been created with thedissolution of electrolytic dissociation of carbonxyl groups of PAA,which facilitate cross linking between PAA and PVA, leading to astronger interconnection between different function groups.

The silicon-based anode active material are particles that include amixture of silicon, graphite, metallic and/or non-metallic oxides, and apolymer coating, which is optional. The ceramic-polymer composite anodetypically includes 60 to 96 wt % and preferably 65 to 80 wt %silicon-based anode material.

With respect to the silicon-based anode active material, it typicallyincludes (i) 40 to 90 wt % and preferably 50 to 60 wt % silicon, (ii) 20to 60 wt % and preferably 5 to 15 wt % graphite, (iii) 5 to 15 wt % andpreferably 7 to 12 wt % metal and/or non-metallic oxides and (vi) 0 to10 wt % and preferably 1 to 5 wt % of a polymer that forms a polymercoating.

Preferred metal oxides also include, for example, SiO, SiO₂, andmixtures thereof; the silicon-based anode active material may alsocontain SiC.

Preferred non-metal oxides include, for example, SiO, SiC, SiO₂, andmixtures thereof.

The optional polymer coating for the silicon-based anode active materialserves as a buffer layer and preferably comprises polyvinyl alcohol(PVA), poly(acrylic acid) (PAA), polyvinylidene fluoride (PVF),polyvinylidene difluoride (PVDF), and mixtures thereof.

A process for fabricating Si-based composite active anode materials isshown in FIG. 1 wherein 40-80% silicon (40-100 μm), 20-60% graphite(40-100 μm), and 5-15% titanium oxide (40-100 nm) are added into aplanetary ball milling machine and milled for 10-100 hours at a millingspeed of 100-400 rpm. The ball-milled precursor is then annealed in anair furnace at the temperature of 200-400° C. for 1-4 hours. To achievethe Si-based composite powder with a uniform particle size, the annealedpowder is sieved through a 100-300 mesh. The sieved Si-based compositeactive material is ready to use to prepare Si-based anodes that areassembled into ASSLiBs.

To form a polymer coating on the Si-based active material which servesas a polymer buffer layer, polyvinyl alcohol (PVA, Mw: 31-98 k, 5-15 wt%) is added to a planetary ball milling machine, along with the sievedSi-graphite-titania composite material in an Argon atmosphere. Ballmilling time is set from 12 hours to 48 hours. The PVA polymer coversthe Si particle surfaces in the ball-milling process. PVA polymer chainswill hold Si particles from huge volume expansion and shrinkage duringthe charge-discharge process in a further resultant lithium-ion battery.This manufacturing procedure for the Si-based composite material issimple, cost-effective, scalable for large-scale production. Theresultant Si-based anode materials made can deliver (1200-3000 mAh/g)much higher (larger than 4 times) specific capacity than traditionalgraphite anode material (372 mAh/g), leading to a high volumetric andgravimetric energy density of the resultant ASSLiB.

FIG. 2A is a scanning electron microscope of pristine Si particles (4-8μm) before processing. FIG. 2B is an SEM image of the Si-based compositeanode active material (Si-graphite-titanium oxide, 45:40:15, weightratio) before coating with a polymer. The composite materials in thisimage were subject to the high energy ball milling in the air atmospherefor 50 hours and annealed at 350° C. for 2 hours before sieving with 100mesh. The primary particle size was reduced to 3-4 μm. FIG. 2C is an SEMimage of a Si-based composite anode active material(Si-graphite-titanium oxide-PVA) that was coated with a PVA polymer byhigh energy ball milling in Ar atmosphere. Si-based composite particlesare wrapped with resilient PVA coatings that covalently bond to Siparticles. The SEM image shows that Si particles are surrounded by finePVA particles.

A silicon-based composite electrode as depicted in FIG. 3 has a polymernetwork or matrix with Si-based anode active materials, conductingagents, lithium ions and ceramic nanoparticles that distributed orinfiltrated within the matrix. The Si-based composite anode with its 3-Dpolymer network structure exhibits (i) enhanced ion-transport and (ii)improved contact with solid electrolytes. Resilient electrolyte surroundthe Si particles will act as a buffer layer to accommodate the volumechange of Si particles during the charge-discharge process.

The active materials for anodes are Si-based composite anodes areinfiltrated with solid-state electrolytes. The solid-state electrolyteis mechanically resilient and high-ionic-conductive. It can form anetworking structure within the anode to compensate for the volumechange of Si particles during charging and discharging. The rigidfeature of ceramic nanoparticles compensates and diminishes thedeformation of Si particles in the course of charging and discharging.The optional polymer coating outside the Si-based composite particlesacts as a buffer layer to Si particles to accommodate the volume changeof original Si particles, resulting from its resilient feature. Thecoating wraps on the Si particle surfaces by covalently bonding. Theseformed covalent bonds enhance the mechanical strength between Siparticles and the coating layer, leading to limited volume change duringthe repeated lithiation and delithiation, thus enhanced stability andlonger cycling life of resultant lithium-ion batteries.

FIG. 4 shows a tape-casting system 2 for preparing the Si-basedcomposite anode. The Si-based composite anode active materials,conducting agent and binder are preferably dried under vacuum beforebeing added into tank 6. A mixture of polymer precursor and plasticizeris added to tank 6 to form a precursor slurry, which also contains 0.001wt % to 1.0 wt % of a photoinitiator such as phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide (819). An adjustable doctorblade 12 coats a wet film 8 of the precursor slurry 4 of the desiredthickness onto the current collector foil 10 which is supported bystationary roll 14. UV radiation directed to wet film 8 from UV source16 initiates in-situ radical polymerization to crosslink the polymerprecursor in the Si-based anode composite 18. The monomer or polymerprecursors polymerize and/or crosslinked, which establishes a polymernetwork that has strong interactions with the other components in theelectrode. Therefore, the polymer matrix can act as a binder andcompletely or partially replace the binder if the weight percentage ofSi-based composite active material is lower than 80%. It has been foundthat ceramic nanoparticles accumulate toward the top of the compositeelectrode so that a ceramic nanoparticle gradient is established withinthe layer along the direction of the thickness. The upper side of thecomposite electrode on which the anode is disposed has a higherconcentration of ceramic nanoparticles which acts as a barrier tolithium dendrite growth. Large dimensional electrolyte-infiltrated,Si-based composite electrode sheets can be processed with awell-established industrial process that is cost-effective, scalable,and compatible with the currently used Li-ion production line. Theresultant Si-based anode sheet can be directly incorporated into themanufacturing of all-solid-state lithium electrochemical pouch cellsthat would offer high energy density, long cycle life, and highcharge/discharge rate.

As an example, to prefabricate an electrolyte-infiltrated compositeSi-based anode by tape-casting method without using a binder, aprecursor slurry comprising 1 wt % to 10 wt % carbon black, 60 wt % to96 wt % Si-based anode material, and 1 wt % to 20 wt % polymer precursorare mixed at 50° C. to 70° C. for at least 12 hours in de-ionized water.The typical water-to-solid ratio is 1 ml to 0.5 g˜1.0 g solid. Theslurry is printed on an anode current collector, typically copper foil,by tape-casting method and the printed sheets are under UV light for 10minutes. Finally, the sheets are dried, calendared, and cut.

Si-based anodes in the present invention can be incorporated intosolid-state lithium-ion electrochemical cells and batteries. A preferredsolid-state polymer electrolyte membrane comprises a ceramic-polymernanocomposite electrolyte that is disclosed in US 2020/0335814, which isincorporated herein by reference. A particularly preferred solid-stateelectrolyte is a ceramic-polymer composite electrolyte membranecomprises: (i) a polymer matrix, (ii) ceramic nanoparticles withdiameters that range from 10 to 2000 nm that are distributed in thepolymer matrix, (iii) a plasticizer (iv) a lithium salt, wherein theceramic nanoparticles are selected from the group consisting of ceramicmaterials having the basic formula Li₇La₃Zr₂O₁₂ (LLZO) and derivativesthereof wherein specific quantities of Al, Ta and/or Nb are substitutedat the Zr sit i es. Derivatives include, for example,Al_(x)Li_(7-x)La₃Zr_(2-y-z)Ta_(y)Nb_(z)O₁₂ where x ranges from 0 to0.85, y ranges from 0 to 0.50 and z ranges from 0 to 0.75, wherein atleast one of x, y and z is not equal to 0, and mixtures thereof.Particularly preferred ceramic nanoparticles areAl_(x)Li_(7-x)La₃Zr_(1.75)Ta_(0.25)O₁₂ (x ranges from 0.01 to 0.85) andLi₇La₃Zr_(2-z)Nb_(z)O₁₂ (z ranges from 0.01 to 0.60).

The polymer matrix, ceramic nanoparticles, plasticizer and lithium saltused for the electrolyte membrane can be the same as those used inpreparing the inventive ceramic-polymer composite Si-based anode. Theceramic-polymer composite electrolyte membrane typically includes 20 to60 wt % lithium salt, 5 to 60 wt % ceramic nanoparticles, 10 to 60 wt %plasticizer, and 10 to 50 wt % polymer matrix. The electrolyte membraneexhibits an ionic conductivity of higher than 1×10⁻⁴ S/cm when measuredat a temperature in the range of −20° C. to 10° C. and higher than1×10⁻³ S/cm when measured at a temperature 20° C. or higher.

As an example, to make a solid-state electrolyte membrane. A precursorsolution consisting of 10 to 50 wt % polymer precursor, 5 to 60 wt %ceramic nanoparticles, 10 to 60 wt % plasticizer, and 20 to 60 wt %lithium salt is mixed by magnetic stirring for 30-60 min, and pouredonto a specifically designed module, with a configuration and size withprecisely controlled geometries. For example, a typical module for coincell has a diameter of 11/16 inch (1.75 cm) and height of 0.02 cm.Another typical module for a pouch cell has a rectangular aperturehaving (L×W×H) dimensions of 6.2 cm×4.6 cm×0.02 cm, respectively.In-situ polymerization is enabled by UV radiation, which is applied tothe film for 10-15 min. It yields a free-standing solid-stateelectrolyte that can be peeled off the module.

Preferred cathodes are ceramic-polymer-infiltrated composite cathodesthat typically include 60 to 96 wt % cathode material, 1 to 15 wt %conducting agent, 0.1 to 10 wt % lithium salt, 0.1 to 5 wt % ceramicnanoparticles, 0.1 to 10 wt % plasticizer, 0.1 to 5 wt % polymer matrixand 0 to 15 wt %, binder. The active cathode materials include anycompatible cathodic material which functions as a positive pole in asolid lithium electrochemical cell. Preferred cathode active materialswhich are compatible with the polymer-based electrolyte comprise, forexample, sulfur (S), LiNi_(0.5)Mn_(1.5)O₄(LNMO), LiFePO₄ (LFP),LiNi_(0.8)Co_(0.1)Mn_(0.1)O₂ (NCM811), LiNi_(0.5)Co_(0.2)Mn_(0.3)O₂ (NCM523) and LiNi_(0.6)Co_(0.2)Mn_(0.2)O₂ (NCM 622) and mixtures thereof.The polymer matrix, ceramic nanoparticles, plasticizer, lithium salt,and binder used for the composite cathode can be the same as those usedin preparing the inventive ceramic-polymer composite Si-based anode.

The active materials for cathodes include any compatible material whichfunctions as a positive pole in a solid lithium electrochemical cell.Preferred cathode active materials which are compatible with thepolymer-based electrolyte comprise, for example, LiFePO₄ (LFP),LiNi_(0.8)Co_(0.1)Mn_(0.1)O₂ (NCM811), LiNi_(0.5)Co_(0.2)Mn_(0.3)O₂ (NCM523) and LiNi_(0.6)Co_(0.2)Mn_(0.2)O₂ (NCM 622), LiNi_(0.5)Mn_(1.5)O₄(LNMO), and mixtures thereof.

As an example, to fabricate an electrolyte-infiltrated composite cathodeby a tape-casting method without using a binder, 1 wt % to 10 wt %carbon black, 60 wt % to 96 wt % LFP, and 1 wt % to 20 wt % polymerprecursors are mixed in N-Methyl-2-pyrrolidone (NMP) solvent. The slurryis printed on a cathode current collector, typically aluminum foil, bytape-casting method and the printed sheets are under UV light for 10minutes. Finally, the sheets are dried, calendared, and cut.

Lithium electrochemical cells and batteries of the present inventionwill have excellent rate performance as well as outstanding cyclingstability (>1000 cycles) over a wide range of temperatures. Batterieswill meet severe specifications for a wide temperature working range,quick charging requirement, and high energy density.

FIG. 5A is an electrochemical cell 20 that includes anelectrolyte-infiltrated Si-based anode 22, a solid-state electrolytemembrane 26, and a cathode 24. The anode and solid-state electrolytedefine a first interface where Si-based anode and solid-stateelectrolyte meet and form intimate contacts. Similarly, the cathode andsolid-state electrolyte define a second interface where cathode andsolid-state electrolyte meet and form intimate contacts. The presence ofthe networking-structure electrolyte in the electrode creates andmaintains good intimate contacts which afford superior ion transport andreduced interfacial resistance. A plurality of electrochemical cells canbe stacked into batteries.

An electrochemical cell can be encapsulated to form a coin cell. Asshown in FIG. 5B, the internal components include spring 72, spacerplate 74, Si-based anode 76, solid electrolyte 78, and LFP cathode 80.The anode shell 70 and cathode shell 82 serve as current collectors onthe exterior surfaces of the cathode and anode. The shells preferablyhave planar external surfaces. As shown in FIG. 5C, an assembled lithiumelectrochemical coin cell 90 has spring 98, spacer 100, anode 102, solidelectrolyte 104, and cathode 106 that are positioned between twoelectrode shells 92, 94. Crimping encases the entire structure with aplastic gasket 96 which electronically separates the shells. Whenconducting a plain plate calendar for coin cells, the cell is placedbetween two dies of the crimping machine, where two dies are wrapped bycopper plate. A high-pressure crimper typically applies a pressure ofabout 100 to 1500 psi.

Electrochemical cells can also be encapsulated to form a pouch cell typebattery as shown in FIG. 5D which includes a plurality of unit cells. Inthis configuration, the pouch cell includes LFP cathode sheets 30 and 32that are connected to cathode current collector 52, anode graphitesheets 36 and 38 that are connected to anode current collector 54, LFPcathode sheets 42 and 44 that are connected to cathode current collector56, and anode graphite sheets 48 and 50 that are connected to anodecurrent collector 58. Solid electrolytes 34, 40, and 46 are positionedbetween the anodes and cathodes as shown.

FIG. 6 shows the structures of a conventional liquid Li-ion battery andof an ASSLiB that has the electrolyte-infiltrated Si-based compositeanode. The electrolyte-infiltrated Si-dominant anode helps achieve highenergy density and fast discharging rate. The mechanically resilient andelectronically high-ionic-conductivity electrolyte form a 3-dimensionalpolymer matrix in the Si-based anode. The networking structure createdby the infiltrated electrolyte creates pathways for lithium ionstransport within the Si anode, and also between the Si anode and thesolid-state electrolyte. These pathways improve the efficiency and therate of Li ion transfer; the ALLLiBs exhibit high-rate capability andhigh specific discharge capacity. The electrolyte-infiltrated Si-anodealso enables intimate contact between the Si anode surface and thesolid-state electrolyte surface due to the strong networking connectionfrom the same polymer in the Si anode and the solid-state electrolyte.This contact between the Si anode layer and the electrolyte layerremains intact during repeated lithiation and delithiation, resulting inlong cycling life (>1000 cycles) of the resultant cell. Furthermore, thehigh specific capacity of the Si-based anode active material in thepresent patent (>1300 mAh/g @0.2 C) is more than 4 times of theconventional graphite anode's (˜314 mAh/g @0.2 C). If batteries with thesame capacity are fabricated, the thickness of Li-ion battery anode withSi-based anode in the present patent can reduce by 75% as compared withconventional graphite anode (only 25% of graphite anode thickness) asillustrated. This arrangement translates the total thickness reductionup to 35-40% (around ⅜ of the total thickness) and about 25-30% weight.

Half coin cells containing a Si-based anode, solid-state electrolytemembrane, and lithium metal electrode were evaluated. The Si-based anodecomprised 60 wt % Si-based active material, 15 wt % PAA-based binder, 5wt % LLZO, 10 wt % solid-state electrolyte, and 10 wt % carbon black.The solid-state electrolyte membrane positioned between the Si-basedanode and lithium comprised 13 wt % polymer matrix that was derived fromPEGDA, 38 wt % EC, 33 wt % LiTFSi and 17 wt %Al_(0.15)Li_(6.85)La₃Zr_(1.75)Ta_(0.25)O₁₂ with diameters that rangedfrom 10 to 2000 nm. The electrolyte infiltrated in the Si-based anodecomprised 15 wt % polymer matrix that was derived from PEGDA, 45 wt %EC, 40 wt % LiTFSi.

FIG. 7A is a charge-discharge profile of the half coin cell with theelectrolyte-infiltrated Si-based anode and solid-state electrolytedescribed above. The Si anode delivers a discharge specific capacity oflarger than 2500 mAh/g at 0.1 C, which is significantly higherperformance than for conventional graphite anode with only 372 mAh/gtheoretical specific capacity. The high capacity of the Si-based anodeenables the reduction in thickness of the anode (35-40%), the weight ofthe anode (25-30%), thus the total weight of resultant Li-ion battery(25-30%), as compared to conventional liquid lithium-ion batteries. Thebattery energy densities have been improved, both volumetrically(140-170%) and gravimetrically (130-150%).

FIG. 7B is a cycling profile of the half coin cell which was tested at0.1 C for the first three cycles and then at 0.2 C for the rest ofcycles. The discharge capacity is steady above 2500 mAh/g at 0.1 C andsteady above 1400 mAh/g at 0.2 C during the tested cycles. The polymermatrix in the Si anode prevents the Si particles from deformation duringthe charge-discharge process, along with the polymer coating on theoriginal Si particles.

Full coin cells with an electrolyte-infiltrated composites Si-basedanode/SSE/electrolyte-infiltrated LNMO cathode was made and tested. Fullcoin cells with electrolyte-infiltrated graphiteanode/SSE/electrolyte-infiltrated LNMO cathode were also made and testedfor comparison. The electrolyte infiltrated Si-based anode designated A1comprised 55 wt % Si-based active material, 20 wt % PAA-based binder, 5wt % TiO₂, 10 wt % solid state electrolyte, and 10 wt % carbon black.The electrolyte infiltrated in the Si-based anode and cathodes comprised15 wt % polymer matrix that was derived from PEGDA, 45 wt % EC, 40 wt %LiTFSi. The solid-state electrolyte membrane positioned between theSi-based anode and cathode comprised 13 wt % polymer matrix that wasderived from PEGDA, 38 wt % EC, 33 wt % LiTFSi and 17 wt %Al_(0.15)Li_(6.85)La₃Zr_(1.75)Ta_(0.25)O₁₂ with diameters that rangedfrom 10 to 2000 nm. For comparison, the electrolyte-infiltrated graphiteanode designated A2 comprised 80 wt % graphite, 12 wt % SSE, 4 wt %PVDF, and 4% carbon black. LNMO cathode comprised 80 wt % graphite, 12wt % SSE, 4 wt % PVDF, and 4% carbon black.

FIGS. 8A and 8B are the charge-discharge profiles of coin cells withgraphite anode and electrolyte-infiltrated Si-based anode, respectively.The solid-state electrolyte and LNMO cathode used in these cells are thesame. The cells were tested at 0.1 C, 0.2 C, 0.5 C, and 1.0 C. The cellwith the electrolyte-infiltrated Si-anode and LNMO cathode deliveredcapacity around 0.15 mAh and shows no capacity reduction when thetesting rate increased from 0.1 C to 1.0 C. The cell with graphite anodeand LNMO cathode only has 0.10 mAh and delivers less capacity when thetesting rate has increased from 0.1 C to 1.0 C. The cells withelectrolyte-infiltrated Si anode can deliver 1.5 times of totalcapacity, comparing with the cell with the traditional graphite anode.The high specific capacity of the Si-based composite anode material(>1300 mAh/g @0.2 C) enables less anode material weight, less volume,and higher delivering capacity of the resultant cells.

FIGS. 9A and 9B are the cycling profiles of coin cells with graphiteanode and electrolyte-infiltrated Si-based anode, respectively. Cellswith LNMO/SSE/Si structure show excellent cycling stability with 95%capacity retention up to ˜150 cycles. The capacity of cells withelectrolyte-infiltrated Si-based anode dramatically increased from 0.10mAh to 0.16 mAh after 10 cycles at 0.2 C while it takes 200 cycles forgraphite anode to show capacity increasing. The stable cyclingperformance of the Si-based anode, resulting from the resilience polymerstructure which is formed by the infiltrated electrolyte. The bufferlayer provided by the polymer networking structure prevented thedeformation of Si particles during the repeated lithiation anddelithiation, leading to long cycling life (>1000 cycles).

Full coins with Si infiltrated by SSE and NCM811 cathode materials weretested. The structure of the full coin cell was anelectrolyte-infiltrated composites Si-basedanode/SSE/electrolyte-infiltrated NCM811 cathode. The electrolyteinfiltrated Si-based anode comprised 60 wt % Si-based active material,15 wt % PAA-based binder, 5 wt % ceramic particles, 10 wt % solid-stateelectrolyte, and 10 wt % carbon black. The electrolyte infiltrated inthe Si-based anode and cathodes comprised 15 wt % polymer matrix thatwas derived from PEGDA, 45 wt % EC, 40 wt % LiTFSi. The solid-stateelectrolyte membrane positioned between the Si-based anode and cathodecomprised 13 wt % polymer matrix that was derived from PEGDA, 38 wt %EC, 33 wt % LiTFSi, and 17 wt %Al_(0.15)Li_(6.85)La₃Zr_(1.75)Ta_(0.25)O₁₂ with diameters that rangedfrom 10 to 2000 nm. NCM811 cathode materials comprised 80 wt % graphite,12 wt % SSE, 4 wt % PVDF, and 4% carbon black.

FIG. 10A and FIG. 10B are rate performance and cycling stability data ofthe full cells which comprised electrolyte-infiltrated Si-basedcomposite anode and NCM811 cathode. The cells were charged/discharged at0.2 C for the first 2 cycles, and 0.5 C for the cycling stability test.Cells delivered 0.25 mAh at 0.2 C and 0.20 mAh at 0.5 C. The maximumcapacity of the cells was 0.25 mAh. The total capacity of the cellsmaintained above 0.15 mAh for the first 100 cycles.

The foregoing has described the principles, preferred embodiment, andmodes of operation of the present invention. However, the inventionshould not be construed as limited to the particular embodimentsdiscussed. Instead, the above-described embodiments should be regardedas illustrative rather than restrictive, and it should be appreciatedthat variations may be made in those embodiments by workers skilled inthe art without departing from the scope of the present invention asdefined by the following claims.

What is claimed is:
 1. A ceramic-polymer composite anode that comprises:(i) a polymer matrix, (ii) ceramic nanoparticles that are distributed inthe polymer matrix, (iii) a silicon-based anode active material that isdistributed in the polymer matrix wherein the silicon-based anode activeparticles comprise 50 to 60 wt % silicon, 5 to 15 wt % graphite, 7 to 12wt % metallic oxides, and 1 to 5 wt % polymer, (iv) a conducting agentthat is distributed in the polymer matrix, (v) lithium salt and (vi)plasticizer.
 2. The composite anode of claim 1 wherein the anode activeparticles include a polymer coating.
 3. The composite anode of claim 1comprising TiO₂ or SiO₂.
 4. The composite anode of claim 1 comprising(i) 1 to 6 wt % polymer matrix, (ii) 1 to 5 wt % ceramic nanoparticles,(iii) 65 to 80 wt % silicon-based anode active material, (iv) 3 to 9 wt% conducting agent, (v) 1 to 5 wt % lithium salt and (vi) 1 to 10 wt %plasticizer.
 5. The composite anode of claim 1 wherein the ceramicnanoparticles are selected from the group consisting of ceramicmaterials having the basic formula Li₇La₃Zr₂O₁₂ (LLZO) and derivativesthereof wherein at least one of Al, Ta or Nb is substituted in Zr sitesof the Li₇La₃Zr₂O₁₂.
 6. The composite anode of claim 5 wherein thederivative is AlxLi_(7-x)La₃Zr_(2-y-z)Ta_(y)Nb_(z)O₁₂ where x rangesfrom 0 to 0.85, y ranges from 0 to 0.50 and z ranges from 0 to 0.75,wherein at least one of x, y and z is not equal to 0, and mixturesthereof.
 7. The composite anode of claim 1 wherein the ceramicnanoparticles comprise Li₇La₃Zr_(2-z)Nb_(z)O₁₂ wherein z ranges from0.01 to 0.60.
 8. The composite anode of claim 1 wherein the ceramicnanoparticles comprise AlxLi_(7-x)La₃Zr_(2-y-z)Ta_(y)Nb_(z)O₁₂ wherein xranges from 0 to 0.85, y ranges from 0 to 0.50, and z ranges from 0 to0.75, wherein at least one of x, y and z is not equal to 0, and mixturesthereof.
 9. The composite anode of claim 1 wherein the ceramicnanoparticles have a tunable size ranging from 10-2000 nm.
 10. Anelectrochemical cell comprising: (a) ceramic-polymer composite anodethat comprises: (i) 1 to 6 wt % of a first polymer matrix, (ii) 1 to 5wt % of a first ceramic nanoparticles that are distributed in the firstpolymer matrix, (iii) 65 to 80 wt % of a silicon-based anode activematerial that is distributed in the first polymer matrix, (iv) 3 to 9 wt% of a first conducting agent that is distributed in the first polymermatrix, (v) 1 to 5 wt % of a first lithium salt and (vi) 1 to 10 wt % ofa first plasticizer; (b) a cathode comprising a cathode active material;and (c) an electrolyte there between.
 11. The electrochemical cell ofclaim 10 wherein the silicon-based anode active material comprises anodeactive particles that include a mixture of silicon, graphite, andmetallic and/or non-metallic oxides.
 12. The electrochemical cell ofclaim 11 wherein the anode active particles include a polymer coating.13. The electrochemical cell of claim 10 wherein the cathode comprises:(i) a second polymer matrix, (ii) second ceramic nanoparticles that aredistributed in the second polymer matrix, (iii) a second lithium salt,(iv) a second plasticizer, (v) a cathode active material that isdistributed in the second polymer matrix, (vi) a second conducting agentthat is distributed in the second polymer matrix; and wherein theelectrolyte comprises a solid-state electrolyte which comprises aceramic-polymer composite electrolyte membrane that comprises: (i) athird polymer matrix, (ii) third ceramic nanoparticles with diametersthat range from 10 to 2000 nm and that are distributed in the thirdpolymer matrix, (iii) plasticizer and (iv) lithium salt, wherein thethird ceramic nanoparticles are selected from the group consisting ofceramic materials having the basic formula Li₇La₃Zr₂O₁₂ (LLZO) andderivatives thereof wherein at least one of Al, Ta or Nb is substitutedin Zr sites of the Li₇La₃Zr₂O₁₂.
 14. The electrochemical cell of claim13 wherein the membrane has an ionic conductivity of higher than 1×10⁻⁴S/cm when measured at a temperature in the range of −20° C. to 10° C.and higher than 1×10⁻³ S/cm when measured at a temperature 20° C. orhigher.
 15. The electrochemical cell of claim 14 wherein the firstpolymer matrix, second polymer matrix and third polymer matrix arederived from the same polymer precursors.
 16. The electrochemical cellof claim 10 wherein the silicon-based anode active particles comprise 50to 60 wt % silicon, 5 to 15 wt % graphite, 7 to 12 wt % metallic oxides,and 1 to 5 wt % polymer.
 17. A solid-state lithium-ion battery having aplurality of unit cells, each unit cell comprising: (a) anelectrolyte-infiltrated composite silicon-based anode that comprises:(i) 1 to 6 wt % of a first polymer matrix, (ii) 1 to 5 wt % of a firstceramic nanoparticles that are distributed in the first polymer matrix,(iii) 1 to 5 wt % of a first lithium salt, (iv) 1 to 5 wt % of a firstplasticizer, (v) 65 to 80 wt % of a silicon-based anode active materialthat is distributed in the first polymer matrix, (vi) 3 to 9 wt % of afirst conducting agent that is distributed in the first polymer matrix,and (vii) 1 to 5 wt % of a first binder if the weight ratio of the anodeactive material is greater than 80 wt %; (b) an electrolyte-infiltratedcomposite cathode that comprises: (i) a second polymer matrix, (ii)second ceramic nanoparticles that are distributed in the second polymermatrix, (iii) a lithium salt, (iv) a second plasticizer, (v) a cathodeactive material that is distributed in the second polymer matrix, (vi) asecond conducting agent that is distributed in the second polymer matrixand (vii) a second binder if the weight ratio of the cathode activematerial is greater than 80 wt %; and (c) interposed the between theanode and the cathode, a solid-state electrolyte which comprises aceramic-polymer composite electrolyte membrane that comprises: (i) athird polymer matrix, (ii) third ceramic nanoparticles with diametersthat range from 10 to 2000 nm and that are distributed in the thirdpolymer matrix, (iii) third plasticizer (iv) third lithium salt, whereinthe third ceramic nanoparticles are selected from the group consistingof ceramic materials having the basic formula Li₇La₃Zr₂O₁₂ (LLZO) andderivatives thereof wherein at least one of Al, Ta or Nb is substitutedin Zr sites of the Li₇La₃Zr₂O₁₂.
 18. The battery of claim 17 wherein thesilicon-based anode active material comprises anode active particlesthat include a mixture of silicon, graphite, and metallic oxides. 19.The battery of claim 18 wherein the anode active particles include apolymer coating.
 20. The battery of claim 17 wherein the silicon-basedanode active particles comprise 50 to 60 wt % silicon, 5 to 15 wt %graphite, 7 to 12 wt % metallic oxides, and 1 to 5 wt % polymer.
 21. Aceramic-polymer composite anode that comprises: (i) 1 to 6 wt % polymermatrix, (ii) 1 to 5 wt % ceramic nanoparticles that are distributed inthe polymer matrix, (iii) 65 to 80 wt % silicon-based anode activematerial that is distributed in the polymer matrix, (iv) 3 to 9 wt %conducting agent that is distributed in the polymer matrix, (v) 1 to 5wt % lithium salt and (vi) 1 to 10 wt % plasticizer.
 22. The compositeanode of claim 21 wherein the anode active particles include a polymercoating.
 23. The composite anode of claim 21 comprising TiO₂ or SiO₂.24. The composite anode of claim 21 wherein the ceramic nanoparticlesare selected from the group consisting of ceramic materials having thebasic formula Li₇La₃Zr₂O₁₂ (LLZO) and derivatives thereof wherein atleast one of Al, Ta or Nb is substituted in Zr sites of theLi₇La₃Zr₂O₁₂.
 25. The composite anode of claim 24 wherein the derivativeis Al_(x)Li_(7-x)La₃Zr_(2-y-z)Ta_(y)Nb_(z)O₁₂ where x ranges from 0 to0.85, y ranges from 0 to 0.50 and z ranges from 0 to 0.75, wherein atleast one of x, y and z is not equal to 0, and mixtures thereof.
 26. Thecomposite anode of claim 21 wherein the ceramic nanoparticles compriseLi₇La₃Zr_(2-z)Nb_(z)O₁₂ wherein z ranges from 0.01 to 0.60.
 27. Thecomposite anode of claim 21 wherein the ceramic nanoparticles have atunable size ranging from 10-2000 nm.